Computers are indispensable to the daily life of people nowadays; hence, keyboards, which are tools of data input, are of vital importance. In general, people usually work with computers in a well-illuminated environment. However, to allow computers to be operable in dark environments, illuminated keyboards were invented. The symbols displayed by conventional illuminated keyboards have to be luminous. To this end, all the parts and components beneath the keys must be light-permeable so as for light rays to be guided to the luminous symbols displayed on the keys. As a result, the conventional illuminated keyboards are structurally complicated, poor in optical performance, uneven in symbol brightness, and difficult to design and manufacture. Moreover, the conventional illuminated keyboards incur high costs and necessitate a lengthy manufacturing process when marketed in different countries and thus required to display symbols, including characters, in the respective languages of the countries. Furthermore, when the conventional illuminated keyboards are operating in bright and dark environments, the luminous symbols displayed on the keys may be hidden by the users' fingers and thus invisible to the users. Also, the appearance of the conventional illuminated keyboards is invariable and thus monotonous. Last but not least, the symbols displayed on the keys of the conventional illuminated keyboards get blurred or smeared after long contact with the users' fingers.
Accordingly, it is imperative to invent a key plate and an illuminated keyboard having the same with a view to simplifying the structure of the illuminated keyboard, cutting its manufacturing costs, shortening its manufacturing process, preventing users' fingers from hiding the symbols displayed on the keys in bright and dark environments, preventing the symbols displayed on the keys of the illuminated keyboard from getting blurred or smeared after long contact with the users' fingers, and rendering the appearance of a key symbol display plate of the illuminated keyboard variable.